"Sandbox gameplay" is one of those ambiguous terms in game development that is used a lot, but rarely defined.

To Matthew Woodward, senior designer at EVE Online developer CCP, "sandbox" is just a mindset in which his studio operates on a daily basis.

"['Sandbox'] is really hard to define, because it's so ingrained in what we do, that we know what it is, but it's hard to put into words," he tells Gamasutra.

But he offers up a pretty good definition anyhow. "Basically it's three things: being social, goal-driven and emergent -- making a game open, giving players control, essentially, and if you're making a multiplayer game, making it as social as possible, because that's why they're playing the game in the first place."

Woodward posits that emergence is likely the most important aspect, and it's something to concentrate on whether you're making a single-player sandbox game or a multiplayer game.

CCP is a studio that knows a thing or two about open-ended MMOs. EVE Online is nearly 10 years old now, and its trademarks are exactly the three elements that Woodward uses to describe sandbox games. EVE's player-driven economy, professions and close ties with the community have all helped the game standout from World of Warcraft copies, and carve a successful niche of its own.

Key to EVE's success is grasping what it means for an MMO to be self-sustaining. Woodward explains CCP's approach. "Essentially, you need the emergence, you need the openness.

"The big enemy is rest states -- a place where players keep on doing the same things over and over again. That's the big thing that's going to drag down your open-endedness. That and obviously if a player can finish [the game], it's not open-ended," he says."

That open-endedness can translate into longevity for an online game. "[The game has to enable] an ongoing balance. Anything that supports competitive-type gameplay, trying to be the best at something, is really good for open-endedness, because you can have that back-and-forth between players, and you always try to get it back when you lose it," says Woodward.

Narrative vs. sandbox

There's one element that is not mentioned in Woodward's definition of "sandbox," or in his explanation of self-sustaining gameplay: narrative. There is in fact a lot of narrative that happens in EVE, but it's primarily player-driven. Woodward is skeptical that game-driven narrative can really work successfully in an MMO.

"It seems to me, from my very EVE-centric perspective, that there's a lot of value in narrative gameplay, and there's a lot of value in MMOs," he says. "It's not crystal clear to me how merging those two things together is the best possible way to enhance them both. It seems like they're pushing in different directions, and trying to be different kinds of games.

"For me, and for the way I look at games, those two types of games are not obvious bedfellows, and I wonder whether what kind of compromises you're making when you're trying to get those to mesh together nicely are worth what you're trying to achieve.

"If you're trying to achieve a single-player experience, it's not obvious to me how that's benefiting from a creative point of view from being embedded in a very highly-social multiplayer game."